Methacrylic acid is useful as a raw material for paint or resin modifying agent, and its esters are an industrially significantly important compound as a raw material for acrylic resin.
As a method for chemical production of methacrylic acid derivatives, the ACH method intermediated by acetone cyanhydrin using cyanide and acetone as a raw material, the C4 oxidation using isobutylene or tert-butanol as a raw material, and the like are practically used. Those chemical production methods rely on fossil fuels and also require a large amount of energy.
Recently, from the viewpoint of preventing global warming and environmental protection, use of renewable biogenous resources (renewable raw materials) as a carbon source to be a substitute of fossil fuels of the related art receives attention. For example, a method for producing 2-hydroxyisobutyric acid and 3-hydroxyisobutyric acid, which are a precursor of methacrylic acid, from a natural product such as sugar using microbes existing in nature has been suggested (see, Patent Documents 1 and 2 and Non-Patent Document 1). However, those methods still rely on a chemical method in terms of the process for producing methacrylic acid by dehydration of a precursor.
Further, although a method for producing methacrylic acid from glucose using a recombinant microbe introduced with plural enzyme genes, which is not exist in nature, has been suggested, it is a mere suggestion of simple combination between known enzyme reactions and imaginary enzyme reactions deduced therefrom, and has not been practically proved (see, Patent Documents 3 to 5).
Meanwhile, as a naturally occurring microbe, a photosynthetic microbe having the ability to produce methacrylic acid is known (Non-Patent Document 2). However, the photosynthetic microbe only converts 3-mercaptoisobutyric acid, which is a special compound not existing in nature, to methacrylic acid.
Further, in Patent Document 6, a method for producing an acrylic acid ester according to an action of a hydrolase in the presence of Acryloyl-CoA and an alcohol is disclosed. It is suggested in the same literature that a methacrylic acid ester can be also similarly produced. However, considering diversity and substrate specificity of an enzyme, it only demonstrates that an acrylic acid ester can be produced with few limited hydrolases, and it remains uncertain whether or not a methacrylic acid ester having a different structure can be also similarly produced by the hydrolase. Further, it remains completely uncertain whether or not production can be made with a different kind of enzyme having a different reaction mechanism. Further, when an ester is synthesized with the hydrolase described in Patent Document 6, it is expected that an ester produced is basically dissociated due to hydrolysis activity, and thus it is difficult to be considered as an effective production method.
Meanwhile, alcohol acyl transferase (hereinbelow, “ATT”) is known as an enzyme for synthesis of fruity flavor. In Patent Document 7, a method for producing various esters as fruit flavor by identifying the gene of the same enzyme, which is contained in specific fruits, is suggested. However, the possibility of synthesizing a methacrylic acid ester with the enzyme is not described and remains completely uncertain.
As described above, although several suggestions or discussions have been made, there is no example showing actual production of methacrylic acid derivatives using microbes, and thus an effective production method needs to be established.